Neosporosis

Neosporosis probably causes over 10% of all abortions in UK
cattle

What is Neosporosis?

Neosporosis is caused by infection with the
protozoa Neospora caninum. Neosporahas
been found world-wide and in many species other than cattle.
Currently abortion due to Neospora has been shown in
cattle, sheep and horses. The dog and other canids (such as
foxes) are the definitive host. That is they are the animals in
which the parasite becomes sexually mature and reproduces.

Clinical Signs

Abortion, between 3 and 9 months of pregnancy (particularly 5 to
7 months)

Still birth or premature calf

Occasionally, calves will have brain disease at birth

No other signs seen in the mother

Repeat abortions possible in the same cow

Diagnosis

Clinical signs of little help

Characteristic heart and brain damage in aborted calf

Identification of parasite in the calf tissue

Antibodies in the mother's blood

However, as a large number of healthy calves can be infected
with Neospora it is important to eliminate other causes of
abortion, particularly BVD or leptospirosis before a diagnosis of
neosporosis is made.

Treatment

No treatment of any proven benefit

Prevention

Dogs are potentially a source of disease. So prevention must
include:

a) Keeping cattle food and water away from dogs and
foxes

b) High hygiene standards at calving. Dispose
of placental membranes and aborted or dead calves before dogs can
get them

However, transmission from mother to calf (known as vertical
transmission) is far more important. Over 90% of calves born to
mothers with antibodies to Neospora will have been
infected in the womb. The importance of transmission between cattle
is less clear. Nevertheless, vertical transmission alone can
maintain infection in a herd. To eliminate Neospora
you need to:

1) Identify infected cattle: All cattle
with antibodies to Neospora are sources of infection
to their calves. Additionally cattle with antibodies are 20 times
more likely to abort between 90 and 270 days of pregnancy than
cattle without antibodies. Finally, on average, several studies
have suggested that infected cows produce less milk than antibody
negative cows.

2) Select only seronegative cattle for
breeding. If you don;t cull seropositive cows, ensure that
you only breed them to beef bulls. Heifers with antibodies
should be sold for meat not bred.

These strategies look expensive to achieve, however the cost of
neosporosis far outweighs the cost of eliminating it from the
herd

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